Turbomachine sparkplug fixing assembly

Abstract

Assembly comprising, on a turbomachine:—a combustion chamber ( 30 ) having a longitudinal axis ( 30 a ) and comprising: internal and external longitudinal walls ( 90 ) having a first opening ( 90 a ) substantially transverse to said axis ( 30 a ), an outer casing ( 110 ) having a second opening ( 110 a ) likewise substantially transverse to said axis ( 30 a ),—a turbomachine sparkplug ( 150 ),—a device ( 130 ) for radially securing the sparkplug ( 150 ), which device ( 130 ) comprises a sparkplug adapter ( 160 ) fixed toward a first end to the outer casing ( 110 ), facing the second opening ( 110 a ) and through which adapter and casing the sparkplug ( 150 ) in question passes, and a sparkplug guide ( 190 ) kept in contact with the external longitudinal wall ( 90 ), facing the first opening ( 90 a ) and through which the sparkplug ( 150 ) passes to emerge in the combustion chamber ( 30 ), the sparkplug ( 150 ) and the sparkplug guide ( 190 ) each having a screw thread ( 103, 105 ), the screw threads ( 103, 105 ) being screwed together so as to stabilize the sparkplug ( 150 ) radially to the axis ( 30 a ) of the combustion chamber ( 30 ) with respect to said external longitudinal wall ( 90 ), and—in this condition, the sparkplug ( 150 ) and the sparkplug guide ( 190 ) are mounted freely with respect to the outer casing ( 110 ) in a direction substantially radial to the axis of the second opening ( 110 a ).

The invention claimed is: 
     
       1. An assembly comprising, on a turbomachine:
 an outer casing; 
 a turbomachine sparkplug; 
 a combustion chamber having a longitudinal axis and comprising:
 an air diffuser means and fuel injector means; 
 an internal longitudinal wall and an external longitudinal wall, the external longitudinal wall having a first opening substantially transverse to the longitudinal axis, the internal and external longitudinal walls defining therebetween an inner volume of the combustion chamber which is fed with fuel through the fuel injector means and with air through the air diffuser means, wherein the internal and external longitudinal walls have orifices therethrough for feeding said inner volume with air issued from an internal annular space and an external annular space, the annular spaces communicating with the air diffuser means, said orifices located, with respect to the longitudinal axis, around the respective internal and external longitudinal walls, the external annular space being surrounded by the outer casing, and the turbomachine sparkplug, which emerges in the inner volume through the first opening, extending across the external annular space, so that the turbomachine sparkplug is cooled by said air circulating in the external annular space; 
 
 said outer casing having a second opening, said second opening having an axis transverse to the longitudinal axis; 
 a device for securing the sparkplug to the turbomachine, substantially radially to the longitudinal axis, which securing device comprises:
 a sparkplug adapter fixed towards a first end to the outer casing, facing the second opening, the sparkplug passing through the sparkplug adapter and the outer casing; and 
 a sparkplug guide kept in contact with the external longitudinal wall, facing the first opening and through which the sparkplug passes to emerge in the inner volume of the combustion chamber, 
 
 wherein: 
 the sparkplug and the sparkplug guide each have a screw thread, the respective screw threads being screwed together so as to stabilise the sparkplug radially to the longitudinal axis of the combustion chamber, with respect to the external longitudinal wall, 
 the sparkplug and sparkplug guide are installed freely in relation to the outer casing and the external longitudinal wall, in a direction substantially radial to the axis of the second opening, 
 the sparkplug is locally surrounded by a collar cooperating with at least one seal arranged in abutment between an inner edge of the sparkplug adapter and the collar, and 
 the at least one seal comprises first and second deformable seals arranged on either side of the collar in order to endure airtightness on either side of the collar, so that when one of the first and second deformable seals expands radially, the other of said first and second deformable seals is compressed. 
 
     
     
       2. The assembly according to  claim 1 , wherein the sparkplug guide is mounted in the external annular space and a substantially axial means of sliding is interposed between the sparkplug guide and an annular boss provided on the external longitudinal wall. 
     
     
       3. The assembly according to  claim 1 , wherein the sparkplug adapter has, towards a second end opposite the first end, holes to allow passage of air between the inside and outside of the sparkplug adapter. 
     
     
       4. The assembly according to  claim 1 , wherein the sparkplug adapter features a first part and a second part are removably assembled together, so as to be able to be disassembled in relation to one another substantially parallel to the axis of the second opening in the outer casing. 
     
     
       5. The assembly according to  claim 1 , wherein the sparkplug and sparkplug adapter are mutually equipped with centering means comprising a bead around the sparkplug. 
     
     
       6. The assembly according to  claim 5 , wherein the centering means comprise a spherical bearing around the sparkplug. 
     
     
       7. A turbomachine comprising the assembly according to  claim 1 . 
     
     
       8. The assembly according to  claim 1 , wherein the sparkplug and sparkplug guide are freely installed to tilt in relation to the outer casing and the external longitudinal wall. 
     
     
       9. The assembly according to  claim 1 , wherein the sparkplug and the sparkplug guide are installed, in said direction substantially radial to the axis of the second opening, at a distance from stops provided on the external longitudinal wall, so that the sparkplug and the sparkplug guide can tilt in relation to the outer casing and the external longitudinal wall. 
     
     
       10. An assembly comprising, on a turbomachine:
 an outer casing; 
 a turbomachine sparkplug having a longitudinal axis; 
 a combustion chamber having a longitudinal axis and comprising:
 air diffuser means and fuel injector means; and 
 an internal longitudinal wall and an external longitudinal wall, the external longitudinal wall having a first opening substantially transverse to the longitudinal axis, the internal and external longitudinal walls defining therebetween an inner volume of the combustion chamber which is fed with fuel through the fuel injector means and with air through the air diffuser means, wherein the internal and external longitudinal walls have orifices there through for feeding said inner volume with air issued from an internal annular space and an external annular space, the annular spaces communicating with the air diffuser means, said orifices located, with respect to the longitudinal axis, around the respective internal and external longitudinal walls, the external annular space being surrounded by the outer casing, and the turbomachine sparkplug, which emerges in the inner volume through the first opening, extending across the external annular space, so that the turbomachine sparkplug is cooled by said air circulating in the external annular space; 
 
 said outer casing having a second opening, said second opening having an axis transverse to the longitudinal axis; 
 a device for securing the sparkplug to the turbomachine, radially to the longitudinal axis, which securing device comprises:
 a sparkplug adapter fixed towards a first end to the outer casing, facing the second opening, the sparkplug passing through the sparkplug adapter and the outer casing; and 
 a sparkplug guide kept in contact with the external longitudinal wall, facing the first opening and through which the sparkplug passes to emerge in the inner volume of the combustion chamber; 
 
 
       wherein:
 the sparkplug and the sparkplug guide each have a screw thread, the respective screw threads being screwed together so as to stabilise the sparkplug radially to the longitudinal axis of the combustion chamber, with respect to the external longitudinal wall, 
 the sparkplug and sparkplug guide are installed freely in relation to the outer casing and the external longitudinal wall, in a direction substantially radial to the axis of the second opening, 
 the sparkplug is locally surrounded by a collar cooperating with at least one seal arranged in abutment between an inner edge of the sparkplug adapter and the collar, 
 the sparkplug and sparkplug adapter are mutually equipped with centering means comprising a bead around the sparkplug, and 
 said centering means are inwardly shifted relative to the collar, on the longitudinal axis of the sparkplug, substantially radially to the longitudinal axis.